Process of treating cast-iron.



irons such as are produced by the charcoal JOSEPH E. JOHNSON, JRI, OF NEW YORK, N. Y.

PROCESS OF TREATING- CAST-IRON.

No Drawing.

Specification of Letters Patent. Application filed August 13, 1913. Serial No. 784,492.

Patented Aug. M, 199141.

To all whom it may concern.

Be it known that I, JosEPrrE. Jo NsoN, J12, a citizen of the United States, residing at New York, in the county of New York and State of New York, have invented certain new and useful Improvements in Processes of Treating Cast-Iron, of which the following is a specification.

This invention relates to a process of treating cast iron in molten condition, and to the product resulting from such treatment, the aim of the invention being to give the desirable qualities of strength, density of grain and chilling properties to the more inexpensive cast irons such as are produced by the coke process of smelting and to other irons which do not possess such qualities, these qualities being now exclusively possessed by the more expensive high grade cast process of smelting. By experiments and analyses I have found that contrary to the universal belief, the desirable qualities possessed by these high grade irons are due to the presence of oxygen therein, which does not. exist in the cheaper coke irons in adequate quantities. The qualities mentioned are possessed more by charcoal iron than by coke iron, and more by cold blast charcoal iron than by hot blast charcoal iron. The temperature at which these irons are made is lower in the order given, coke iron being made at the highest temperature, hot blast charcoal iron at the next highest temperature and cold blast charcoal iron at the lowest temperature. The

' affinity of carbon and silicon for oxygen increases with temperature, hence the oxygen which can and does exist in the cold blast charcoal iron does so to a less extent in hot blast charcoal iron and to little or no extent in coke iron.

My invention is therefore directed to the introduction of oxygen into cast irons so that they will possess the desirable qualities mentioned, and the invention consists in so treating the molten iron that it will contain, in addition to the introduced oxygen, a proper amount of carbon and silicon. On account of the afiinityof oxygen for silicon and carbon under high temperatures, the

introduction of oxygen in any available form the desired qualities.

silicon is customarily added than would be into the molten bath at such temperatures as exist in a blast furnace operating with coke, would result in the burning out or oxidization of the silicon and carbon and the consequent elimination of the oxygen; andin order that the product produced by my method may have its proper content of oxygen, silicon and carbon, I propose to introduce the oxygen to the molten bath at a considerably reduced temperature. Under these conditions the carbon will not be materially affected, and if the iron contains little or no silicon it will readily absorb the oxygen. As long as silicon is present however in the bath to a considerable extent, it'will attack and eat up any oxygen that may be introduced, until the silicon is oxidized out to a point where it will cease to combine with the oxygen, which point will vary with different conditions and temperatures. My invention therefore contemplates also the supply ofthe oxygen with an oxidizing effect until this point is reached, and then the continued supply of oxygen with an exygena-ting efi'ect so as to permit the iron to absorb the proper amount of oxygen for the purposes in view. Under these conditions the oxygen will be retained by the iron, if the temperature of the bath is kept down, and the addition of silicon to the bath can then be made and still leave suilicient oxygen present to give Consiredably more necessary to remove all the oxygen present, but the reaction between the two does not proceed to completion because of the low temperature; therefore the desired amount of oxygen remains as well as silicon. In this way a product is made consisting of coke iron containing oxygen, carbon and silicon,

,which product I have found by tests, experiments and analyses to possess the very desirable qualities of strength, density of grain and chilling properties heretofore exclusively possessed by the high grade irons.

I am aware that many patents have been granted describing the introduction of oxygen in many different forms into a bath of molten cast iron for the purpose of changing the molten cast iron into steel or wrought or malleable iron, the action of the oxygen being to oxidize out of the iron those ingredient-s such as carbon, silicon and phosphorus which gave the iron its characteristics as cast iron. My process is to be clearly distinguished from such methods of procedure, as I aim to incorporate a certain quantity of oxygen, while at the same time retaining the proper content of the characteristic elements such as silicon and carbon.

My improved method may be carried into effect in many different ways, the following manner of procedure being one by way of example, and one which has been found to answer to a satisfactory degree the result aimed at. A bath of ordinary cast iron outside the blast furnace at'a reduced temperature, is oxidized by any suitable oxidizing agent either solid, liquid or gaseous, down to the point where the silicon no longer protects the bath from the oxidizing influence. After this point is reached, still more oxygen is introduced into the bath and is absorbed thereby, and finally silicon is added in proper quantity. A convenient manner of carrying out this process, more particularly with reference to introducing the silicon, is to divide a bath of the molten iron into two portions, oxidize and oxygenate one portion so as to free the same of silicon and incorporate the proper amount of oxygen, and then mix with this treated portion, the other untreated portion containing silicon, by which mixing the entire body of metal will possess the necessary amount of oxygen, silicon and carbon to give it the desirable characteristics of high grade irons. Y

My invention can be carried into effect by starting with a white iron free from silicon, and containing the usual amount of carbon characteristic of castiron. .A bath of this white iron when treated at the proper reduced temperature with oxygen, will absorb the latter without the'carbon being materially affected, and then silicon can be added in proper quantity to impart its desirable properties to the mixture.

It will be understood that while I have referred to my process as being particularly applicable to the treatment of coke irons to give the same the improved qualities mentioned, it will be understood that the process may be applied also for the treatment of other irons which like coke irons do not possess such qualities, that is to say, all

irons made at too high'temperature to per-,

mit their retention of the oxygen necessary to give the desired qualities. Included in this class .of irons for instance, is hot blast charcoal iron.

Having thus described my invention what I claim is:

1. The process of treating cast iron, which consists in adding oxygen and silicon to a bath of the same, while maintaining the temperature low enough to permit the retention of oxygen by the bath with a minimum elimination of carbon.

2. The process of treating cast iron, which consists in providing a bath of said iron, incorporating oxygen therein at a temperature sufiiciently low to permit the retention.

of oxygen and a minimum elimination of carbon, providing a second bath of iron coii'e.

silicon, and mixing said baths to-b;

tainlng gether. I 3. The process of treating cast iron, which consists in oxidizing a bath of said'iron 'at'atemperature which willcause the silicon" consists in adding silicon to a bath of said iron containing oxygen, the addition of the silicon being under such conditions that oxygen will be retained by the bath.

6. The process of treating cast iron, which consists in providing a bath of said iron free or substantially'free from silicon, oxygenating said bath, and-finally adding silicon thereto.

7. The process of treating cast iron, which consists in first removing the silicon from the molten iron, then oxygenating the iron, and finally addingsilicon thereto.

8. The process of treating cast iron, which consists in oxidizing from a bath of said iron, the silicon down to a point at which it Y T;

.will no longer prevent the absorption of oxygen by the iron, then oxygenating the bath, and finally adding silicon thereto.

9. The process of treating cast iron, which consists in oxidizing out the silicon from a molten bath ofsaid iron, oxygenating the bath to the saturation point, and then adding' silicon thereto.

10. The process of treating molten cast iron, which consists in introducing into a bath of said iron, a suflicient quantity of oxygen to burn out the silicon, adding additional oxygen to the bath, and finally adding silicon thereto.

11. The process of treating cast iron, which consists in introducing into a molten bath of said iron, a quantity of oxygen sufficient to burn outthe silicon, oxygenating .the bath to the saturation point while retaining the temperature low, and finally adding silicon thereto.

4 12. The process of treating cast iron,

In testimony whereof I have affixed my signature 1n presence of two Witnesses.

JOSEPH E. JOHNSON, Jr

Witnesses:

WM. J. DOLAN, W. R.-KENNEDY. 

